MYSTERY OF CHEMISTRY
This session offers you a collection of Chemistry Questions which test your knowledge. In this post I have include some interesting basic Chemistry. Chemistry is the branch of science that deals with the composition , structure and properties of matter. This is the short key notes for Board (ICSE and CBSE) Preparation to score high marks.
1-M is
an element in the form of a powder. M burns in oxygen and the product obtained
is soluble in water. The solution is tested with litmus. Write down only the
word which will correctly complete each of the following sentences.If M is a
metal , then the litmus will turn..........?
(a) M is
a non-metal , then the litmus will turn.......?
(b) If M
is a reactive metal. then........ will be evolved when M reacts with dilute
Sulphuric acid.
(c) If M
is a metal , it will form........oxide , which will form.........solution with
water.
(d) If M
is a non-metal, it will not conduct electricity in the form of..........?
2- For
each of the salt : A , B , C , and D , suggest a suitable method of its
preparation.
(a)
A is a sodium salt.
(b)
B is a insoluble salt.
(c)
C is a soluble salt of copper.
(d)
D is a soluble salt of Zinc.
3- A
solution has a pH of 7. Explain how you would increase its pH and decrease its
pH.
4-
Solution P has a pH of 13 , solution Q has a pH of 6, and solution R has a pH
of 2. Which solution:
(a)will
liberate ammonia from ammonium sulphate on heating ?
(b)is a
strong acid?
(c)contains
molecules as well as ions?
5- Pick
out the correct answer in the following list : Sodium carbonate , anhydrous
calcium chloride , copper sulphate - 5 - water.:-
(a)What
name is given to the water in the compound copper sulphate - 5 - water ?
(b)If
copper sulphate - 5 - water is heated , anhydrous copper sulphate is formed.
What is its color ?
(c)By
what means , other than heating , could you dehydrate copper sulphate - 5 -
water andobtain anhydrous copper sulphate.
(d)Which
one of the salts in the given list is deliquescent?
6 - From
the formula listed below , choose one , in each case , corresponding to the
salt having thegiven description :- AgCl , CuCO₃ , CuSO₄ 5H₂O, KNO₃ , NaCl,
NaHSO₄ , Pb(NO₃)₂ , ZnCO₃ , ZnSO₄.7H₂O.
(a)An
acid salt.
(b)An
insoluble chloride.
(c)On
treating with concentrated sulphuric acid , this salt changes from blue to
white.
(d)On
heating , this salt changes from green to black.
(d)This
salt gives nitrogen dioxide on heating.
7 - What
will be the effect of the following solutions on blue litmus ?
(a)Aqueous
solution of sodium carbonate.
(b)Aqueous
solution of magnesium chloride.
8 - Why
solid ferric chloride is stored in air tight bottles?
9 - From
the list of metals given below , select a metal whose hydroxide is soluble in
sodium hydroxide solution ; Calcium , magnesium , iron , zinc.
10 - Give
the name and formula of the acid salt which gives sodium ions and sulphate ions
in solution.
11 -
State your observations when :
(a)Lead
nitrate solution and sodium chloride solution are mixed.
(b)Zinc
chloride solution , zinc nitrate solution and zinc sulphate solutions are added
individuallyto barium chloride solution and lead nitrate solution.
12 -
Write the probable color of the following salts.
(a) Ferrous
salts
(b) Ammonium
salts
(c) Cupric
salts
(d) Calcium
salts
(e) Aluminium
salts
13 - On
adding dilute ammonia solution to a colorless solution of a salt , a white
gelatinous precipitate appears. This precipitate however dissolves on
addition of excess of ammoniasolutions.
(a) Which
metal salt solution was used ?
(b) What
is the formula of the white gelatinous precipitate obtained ?
14 - You
are provided with two reagent bottles marked A and B. One of which contains
NH₄OH solution and the other contains NaOH solution. How will you identify them
by a chemical test.
15 - how
will you distinguish lead carbonate and zinc carbonate in solution ?
16 - A
solution of cane sugar does not conduct electricity , but a solution of sodium
chloride is a good conductor.
17 - Why
can't we store AgNO₃ solution in copper vessel ?
18 - When
a dilute aqueous solution of sodium chloride is electrolysed between platinum
electrodes,hydrogen gas is evolved at cathode but mettalic sodium is not
deposited. Why?
19 - A
solution of caustic soda (NaOH) in water or when fused conducts an electric
current. What is the similarity in these two cases ?
20 -
Guess the blanks - The electroplating an articles with nickel requires an.......which
must be a solution containing......ions. The article to be plated is
placed as the........ of the cell in whichthe plating is carried out. The.....
of the cell is made from pure nickel.The ions that are attracked to the
negative electrode and discharged are called...
21 -
Element X is a metal with a valency 2. Element Y is a non-metal with a valency
of 3.
(a) Write
equations to show how X and Y form ions.
(b) If
Y is a diatomic gas , write the equation for the direct combination of X and Y
to form acompound.
(c) If
the compound form between X and Y is melted and the electric current passed
through the molten compound , the element X will be obtained at the........and
Y at the.......of the electrolyticcell.
22 - What
kind of particles will be found in a liquid compound which is a non-
electrolyte?
23 -
Explain why (a) Cu , though a good conductor of electricity is a non-
electrolyte (b) solidsodium chloride does not allow electricity to pass
through.
24 - (a)
Here is an electrode reaction :
Cu
→ Cu ²⁺+2e⁻
(a)
At which electrode ( anode or cathode ) would such a reaction take place ? Is
this an example ofoxidation or reduction ?
(b) A
solution contains magnesium ions (Mg²⁺) , Iron (∣∣) ions (Fe²⁺) and copper ions
(Cu²⁺). On passing a electric current through this solution which ions
will be the first to be discharged atthe cathode ? write the equation for the
cathode reaction ?
(c) Why
is carbon tetra chloride , which is a liquid , a non-electrolyte ?
25 - A
metal article is to be electroplated with silver. The electrolyte selected is
sodium argentocyanide.
(a) What
kind of salt is sodium argentocyanide ?
(b) Why
is it preferred to silver nitrate as a electrolyte ?
(c) State
one condition to ensure that the deposit is smooth , firm and long lasting.
(d) Write
the reaction taking place at the cathode.
(e) write
the reaction taking place at anode.
26 - A
compound which liberates reddish brown gas around the anode during electrolysis
in its molten state.
27 -
Three different electrolyte cells A , B and C are connected in separate
circuits. Electrolytic cellA contains sodium chloride solution. When the
circuit is completed a bulb in the circuit glowsbrightly. Electrolytic cell B
contains acetic acid solution and in this case the bulb in the circuitglows
dimly. The electrolytic cell C contains sugar solution and the bulb does not
glow. Give areason for each of these observations.
28 - Why
are Alkali metals kept in kerosene oil ?
29 -
Metal A has electronic configuration of 2 , 8 , 1 and B has 2, 8 , 8 , 2 which
is a more reactive metal.
(a)
Identify A and B and give their reactions with dil. HCl and dil. H₂SO₄.
(b)
Give the effect of heat on their : (1) Oxide (2) Hydroxides (3) Carbonates (4)
Nitrates.
30 - A
student has been collecting silver coins and copper coins. One day she observed
black coating on silver coins and a green coating on copper coins. which
chemical phenomenon is responsible for these coatings ? write the name of
black and green coatings.
31 - Some
metallic oxides can be reduced by hydrogen , carbon , and carbon monoxide and
some cannot. Explain.
32 -
Aluminium is a more active metal than iron , but suffers less corrosion. Why ?
33 - Why
Aluminium vessels should not be cleaned with powders containing alkalis ?
34 - Nitric acid can be stored in aluminium containers.
35 - From the metals : copper , iron , magnesium , sodium and zinc
select a different metal in each case which :
(a) does not react with dilute hydrochloric acid.
(b)can form 2⁺ and 3⁺ ions.
(c) has a hydroxide that reacts with both acids and alkalis.
(d) does not react with cold water but reacts with steam when heated.
36 - Name an element which reacts with hydrogen to form a compound which
is strongly acidic in water.
37 - Explain why dilute hydrochloric acid can not be concentrated by
boiling beyond 22.2%.
38 - Black metallic oxide which reacts with hydrochloric acid to give a
coloured solution.
39 - Solution A reacts with an acid B (which gives greenish yellow gas
on reacting with oxidisingagents like Pb₃O₄) to give white precipitate C
insoluble in nitric acid but soluble in ammonium hydroxide. Name A , B ,
and C.
40 - A substance 'A' was heated with slaked lime and a gas 'B' with a
pungent smell was obtained. Name the substance A and B.
41 - A gas 'P' gives dense white fumes with chlorine. its aqueous
solution gives a blue color with copper (𝖨𝖨) hydroxide. (a) Name
the gas P. (b) Give its formula. (c) Give three uses of P.
42 - Ammonium solution in water gives a blue precipitates when it
combines with a solution of copper salt. The blue precipitates further
dissolves in excess of ammonia solution to give azureblue solution. Explain
with equation.
43 - A gas 'A' reacts with another gas 'B' in the presence of a catalyst
to give a colorless gas 'C'. Thegas 'C' when comes in contact with air produces
a brown gas 'D'. The solution of 'A' in waterturns red litmus blue. Explain the
observations.
44 - In the preparation of nitric acid from KNO₃ concentrated
hydrochloric acid is not used in place of concentrated sulphuric acid.
Explain why ?
45 - Nitric acid can not be concentrated beyond 68% by the distilltion
of a dilute solution of HNO₃. State the reason.
46 - What is passive Iron ?
47 - The action heat on the blue crystalline solid A gives a reddish
brown gas B ,a gas which re- lights a glowing splint and leaves a black
residue. When gas C which has a rotten egg smell , ispassed through a solution
of A , a black precipitate is formed.
(a) Identify A , B and C
(b) Write equation for action of heat on A.
(c) Write equation between solution of A and gas C.
48 - Why only all glass apparatus should be used for the preparation of
nitric acid by heatingconcentrated sulphuric acid and potassium nitrate.
49 - A dilute acid B does not normally give hydrogen when reacted with
metals but does give a gaswhen reacts with copper. Identify B.
50 - Why a piece of wood becomes black when concentrated sulphuric acid
is poured on it ?
51 - Give reason - Brisk effervescence is seen when oil of vitriol is
added to sodium carbonate.
52 - How do the boiling point and melting point change in the homologous
series of Alcohols ?
53 - Why is pure acetic acid known as glacial acetic acid ?
54 - The two gases A and B are bleaching agents. A is greenish yellow
and bleaches due to itsoxidising property while B a colorless gas bleaches due
to reduction. Identify A and B.
55 - Name the anion present in each of the following compounds :-
(a) Compound A when warmed with concentrated sulphuric acid gives a gas
which fumes inmoist air and which gives dense white fumes with ammonia.
(b) When barium chloride solution is added to a solution of compound B,
a white precipitate insoluble in dilute hydrochloric acid is formed.
(c) The action of heat on the insoluble compound C produces a gas which
turns lime water turbid.
(d) Compound D when warmed with dilute sulphuric
acid gives a gas which turns acidifieddichromate solution green.
56 - Sodium hydroxide solution is added to solution A. A white
precipitate is formed which insoluble in excess of sodium hydroxide solution.
What is the metal ion present in solution A ?
57 - When ammonium hydroxide is added to solution B , a pale blue
precipitate formed. This pale blue precipitate dissolves in excess
ammonium hydroxide giving an inky blue solution. Name is the cation
present in solution B ? What is the probable color of solution B ?
58 - When an ammonium salt is warmed with sodium hydroxide solution,
ammonia gas is evolved.State three ways in which you could identify this gas ?
59 - Identify the substance :-
(a) 'A' is a white solid. When heated heated produces white fumes
(sublime).
(b) 'A' and 'B' on warming produce an alkaline gas.
(c) On adding water to 'C' heat is evolved and 'B' is formed.
(d) 'D' burns brightly in the air to form 'C'.
(e) When 'E' is heated , it gives off brown fumes and leaves a
black residue of 'F'.
(f) A solution of 'G' is formed by warming 'F' with dilute nitric
acid.
(g) 'H' is a gaseous non metallic element that reacts with
hydrogen to form ''I.
(h) A solution of 'I' will neutrallise the solution of 'B'.
60 - Among these salts solutions( A to F) pick out the answers the
questions ;-
A. Copper nitrateB. Iron (II) sulphate C.Iron (III) chloride D. Lead
nitrateE.Magnesium sulphate F. Zinc chloride
(a) which two solutions will give a white precipitate when treated with
dilute hydrochloric acidfollowed by barium chloride solution ?
(b) Which two solution will give a white precipitate when treated
with dilute nitric acid followedby silver nitrate solution.
(c) Which solution will give a white precipitate when either
dilute hydrochloric acid or dilutesulphuric acid is added to it.
(d) Which solution becomes a deep inky blue color when excess of
ammonium hydroxide is added to it.
61 - Select from the list given (A to E) one substance in each case
which matches the description given in parts (a to b).
A.Nitroso Iron (II) sulphate B. Iron (III) chloride C.Chromium
sulphate D.Lead (II)chloride E.Sodium chloride
(a) A compound which is deliquescent.
(b) A compound which is insoluble in cold water , but soluble in hot
water.
(c) The compound responsible for the brown ring during the brown test of
nitrate ion.
(d) A compound whose aqueous solution is neutral in nature.
(e) The compound which is responsible for the green coloration
when sulphur di oxide is passed through acidified potassium dichromate
solution.
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